ZEEWEII DSO1511G not showing square at 2mhz when other people's do.

[slikvik]

Calibrated my probe as per the manual and following along exactly to the calibration in Adrian's Digital Basement video.

• It looks fine a 1Khz (see attachment)
• Switching to 2Mhz looks like the second attachment.
• Adrian's Digital Basement did exactly the same and got a much better square when viewing 2Mhz from the signal generator. (3rd attachment)
  

The review on this forum also showed a pretty good 2mhz square: https://www.eevblog.com/forum/testgear/dso1511e-review/

Do I have a dud version of the device?

[tunk]

What's your signal generator? - it could be caused by it.

[Aldo22]

• Switching to 2Mhz looks like the second attachment.

If you are using the internal signal generator, I can't see how that is connected.

[wasedadoc]

What's you signal generator? - it could be caused by it.

The generator is probably the one in the scope but OP should confirm that.

[csuhi17]

Use it's own signal generator, it knows up to 2Mhz.
Why and what is the ground of your signal generator connected to??

[slikvik]

Yes, I'm using the internal SG which goes to 2Mhz.
The poles at the top are the positive and ground poles for the SG.

This is the exact same setup, settings and test as Adrian's Digital Basement and in the eevblog Product review linked above, both showing a decent square at 2Mhz from the internal SG.

I'd like to know if I can either fix it or do I need to get it replaced?

[Aldo22]

I'd like to know if I can either fix it or do I need to get it replaced?

I would first check whether the problem is the signal generator, the probe or the oscilloscope.

Do you have another signal source in this frequency range?
Do you have another cable or another probe?

Whether you can fix it depends on your skills.
Personally, I would return it if it is new.

[slikvik]

I don't have anything else unfortunately. Attached is the response I got via Aliexpress.

I assume the device is still workable for a novice even with the attenuation in the Mhz range?

Sending it back could probably result in the replacement being the same. Shame that I've seen evidence of GOOD 2 Mhz square on the same device. 

[Aldo22]

If the signal generator is the cause, then it may be acceptable.
If the scope is doing this, then it's not acceptable in my opinion.

I have the similar 2-channel variant DSO2512G and it looks like this:

[csuhi17]

...

[Aldo22]

@csuhi17

Is this the internal signal generator?
Why is yours above 3Vpp?
All others plus the specification is at approximately 2.5V?

[csuhi17]

Yes, its own generator.
with alligator clip, 1x and 10x measuring probe.

Seen with Rigol 3Vpp
Sigpeak says 2.8Vpp.

Because I tested it with the 100 Mhz measuring probe supplied with Fnirsi in the pictures

[slikvik]

Dammit...mine really doesn't look great does it?

If it was the SG, I wouldn't care as I'd hardly use it, but if it's the scope I'm not happy about it!

Unfortunately, I can't tell.

Returning is going to be a pain and, as I showed in the screenshot of my second post, they're saying "They all look like that"

[csuhi17]

wouldn't a fast edge be enough for him to make sure that the scope part is good?

100ns/div
for example single trigger and touching the terminals of a battery with the probe.

[tunk]

The specs for these small scopes tends to be a bit optimistic:
2MHz is the max for the generator so it could be that.
How does it look at e.g. 0.5 or 1 MHZ?

[csuhi17]

Would its quality have deteriorated that much? As a Sigpeak, it was even better quality.
https://youtu.be/qdz101PJ6Oo?si=MCkhs0gscd7Dra_T&t=239

[Fungus]

Is the probe switchable?

Is it set to 1x mode?

[wasedadoc]

Is the probe switchable?

Is it set to 1x mode?

The OP's second photo shows the scope displaying 'x10'.  If the probe was set to x1, the scope would not be showing the amplitude as a few volts.

[slikvik]

Just so you all know....this is the response I got from Zeeweii when trying to return. For you guys in the know, does this make sense:

"Hello, recently we have made a big upgrade to the DSO1511G（The new version has increased memory depth, supports a 6-digit frequency meter and pulse counter, and FFT supports cursor measurements...）. The 1.3Mhz~3.3Mhz square wave is not flat enough and only appears in the new version."

[Aldo22]

So the problem is with the oscilloscope and not the signal generator?
I'm not experienced enough to judge how bad this is for practical use, but it's certainly not an improvement.

What does it look like at 1MHz?

P.S. Out of curiosity, I took a look at the signal from my Zeeweii SG on the benchtop scope and it looks pretty clean.

[slikvik]

Attached is at 1 Mhz.

What do you think of the comments they made above? I don't understand any of those changes.

[Aldo22]

Attached is at 1 Mhz.

1MHz looks better.

What do you think of the comments they made above? I don't understand any of those changes.

I do not know. If these features are not described in the manual, ask Zeeweii for an explanation.

[slikvik]

Thanks. I think I'll keep it! Not sure I need 2 MHz fixing 8bit and 16bit computers anyway.